Self-Assembled Multinuclear Complexes Incorporating 99mTc

Multinuclear complexes or clusters are rarely investigated in medicinal inorganic chemistry although they represent structural intermediates between molecules and nanomaterials. We present in this report two strategies towards Tc-99m-containing clusters. In a pre-assembly approach, the preformed but incomplete cluster fragment [Re-3(mu(2)-OH)(3)(mu(3)-OH)(CO)(9)](-) reacts with [Tc-99m(CO)(3)](+) to the highly stable [(TcRe3)-Tc-99m(mu(3)-OH)(4)(CO)(12)] cube. The same structure self-assembles when reacting the mononuclear Re and Tc-99m precursors in one pot. Integrating the coordinating OH groups from Schiff bases in this concept leads straight to dinuclear, mixed-metal complexes of the type [(TcRe)-Tc-99m(mu(2)-O<^>N-R-1)(2)(CO)(6)] in quantitative yields. Both strategies are unprecedented and open a future path towards clusters, incorporating a Tc-99m radiolabel while being decorated with targeting or cytotoxic moieties.